MEMS electrical contact systems and methods

ABSTRACT

A microelectromechanical systems (MEMS) device may be provided with one or more sintered electrical contacts. The MEMS device may be a MEMS actuator or a MEMS sensor. The sintered electrical contacts may be silver-paste metalized electrical contacts. The sintered electrical contacts may be formed by depositing a sintering material such as a metal paste, a metal preform, a metal ink, or a metal powder on a wafer of released MEMS devices and heating the wafer so that the deposited sintering material diffuses into a substrate of the device, thereby making electrical contact with the device. The deposited sintering material may break through an insulating layer on the substrate during the sintering process. The MEMS device may be a multiple degree of freedom actuator having first and second MEMS actuators that facilitate autofocus, zoom, and optical image stabilization for a camera.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/585,172 filed Dec. 29, 2014, which is a Continuation-in-Part ofInternational Patent Application No. PCT/US14/64445 filed Nov. 6, 2014,which claims priority to and the benefit of U.S. Provisional PatentApplication No. 61/902,748, filed Nov. 11, 2013, all of which areincorporated herein by reference in their entireties.

U.S. patent application Ser. No. 14/585,172 is also aContinuation-in-Part of U.S. patent application Ser. No. 13/840,576filed Mar. 15, 2013, which is a Continuation-in-Part of U.S. patentapplication Ser. No. 12/946,515 filed Nov. 15, 2010 and U.S. patentapplication Ser. No. 13/247,898 filed Sep. 28, 2011 (now U.S. Pat. No.8,768,157 issued Jul. 1, 2014) and which also claims priority to and thebenefit of U.S. Provisional Patent Application No. 61/622,480, filedApr. 10, 2012, all of which are incorporated herein by reference intheir entireties.

U.S. patent application Ser. No. 14/585,172 is also aContinuation-in-Part of U.S. patent application Ser. No. 14/042,214filed Sep. 30, 2013, which is a continuation of U.S. patent applicationSer. No. 12/946,396 filed Nov. 15, 2010 now U.S. Pat. No. 8,547,627issued Oct. 1, 2013, all of which are incorporated herein by referencein their entireties.

TECHNICAL FIELD

One or more embodiments relate generally to microelectromechanicalsystems (MEMS) and, more particularly, to electrical contacts for MEMSdevices.

BACKGROUND

Microelectromechanical systems (MEMS) devices such as MEMS actuators andMEMS sensors are well known. MEMS devices can be made using variouswafer level processing techniques. Electrical contacts for MEMS devicesare often formed using metal sputtering and patterning processes duringwafer fabrication. MEMS devices in particular often include movable oractuatable portions that have to be released in an etch process afterwafer fabrication.

In some situations, if care is not taken, etch processes of this type orother wafer fabrication processes such as high-temperature processes cannegatively affect metal contacts formed during wafer fabrication. Insome cases, metal contacts for MEMS devices are formed after releaseusing a shadow mask during evaporation of released wafers or dies.However, shadow masking operations of this type can be prohibitivelyexpensive and/or labor intensive.

It would therefore be desirable to provide improved electrical contactsfor MEMS devices.

SUMMARY

In accordance with an embodiment, a MEMS device may include one or moreelectrical contacts for electrically connecting the MEMS device toexternal circuitry. The electrical contacts may be metalized electricalcontacts such as silver-paste metalized electrical contacts or otherelectrical contacts formed by sintering a material on the MEMS device.Sintering material may include a metal paste such as a silver paste, ametal preform, a metal powder, a metal ink, or other suitable materialsor combinations of materials for forming metal contacts by sintering ona MEMS device. Electrical contacts such as silver-paste-metalizedcontacts can be formed on a surface of the MEMS device, on an extendedportion of an edge of the MEMS device, or otherwise disposed on the MEMSdevice. Sintered electrical contacts such as silver-paste-metalizedelectrical contacts can be formed on any suitable MEMS device such as aMEMS sensor or a MEMS actuator. External circuitry may include leadlines, printed circuits such as printed circuit boards, or othercircuitry that can be coupled to the MEMS device through the sinteredelectrical contacts.

Electrical contacts formed by sintering material on a MEMS device may beformed by providing a wafer of unsingulated MEMS devices, performingprocessing operations such as etching operations to release actuatingportions of the MEMS devices on the wafer, depositing sintering materialon the released MEMS wafer, and sintering the sintering material byheating the wafer. In this way, metal contacts that may be adverselyaffected by semiconductor processing operations such as etchingoperations can be formed on a MEMS device after etching operations torelease moving portions of the MEMS device have been completed. Thewafer may be singulated to form individual MEMS devices before or aftersintering operations.

In accordance with an embodiment, a device can comprise at least onefirst MEMS actuator configured to move a platform in translation along afirst axis. At least one second MEMS actuator can be configured to movethe platform in a direction that is generally perpendicular to the firstaxis. The device can include at least one silver-paste-metalizedelectrical contact. The silver-paste-metalized electrical contact may bean extended portion of an actuator that includes a silver paste dotconfigured to be attached to a lead line using conductive epoxy.

In accordance with an embodiment, the device may include a firstsilver-paste-metalized electrical contact configured to be connected toa control lead line for supplying a control voltage using conductiveepoxy and a second silver-paste-metalized electrical contact configuredto be connected to a reference lead line for supplying a referencevoltage using conductive epoxy.

In accordance with an embodiment, an actuator assembly can comprise atleast one first MEMS actuator configured to move a platform intranslation and at least one second MEMS actuator configured to move,e.g., rotate, the platform tangentially.

In accordance with an embodiment, a MEMS actuator assembly can comprisea plurality of nested actuators configured to focus a camera and toprovide optical image stabilization for the camera.

In accordance with an embodiment, a method for operating a camera cancomprise moving a platform in translation with at least one first MEMSactuator and moving the platform tangentially with at least one secondMEMS actuator.

In accordance with an embodiment, a multiple degree of freedom actuatorcan comprise a fixed frame, a platform that is movable with respect tothe fixed frame, and three independently movable MEMS actuatorsinterconnecting the fixed frame and the platform. The three MEMSactuators can be configured to cooperate to move the platform in threedegrees of freedom.

In accordance with an embodiment, a method can comprise providing aplatform that is movable with respect to a fixed frame. The platform canbe moved in three degrees of freedom using three independently movableMEMS actuators.

The scope of the invention is defined by the claims, which areincorporated into this Summary by reference. A more completeunderstanding of embodiments of the invention will be afforded to thoseskilled in the art, as well as a realization of additional advantagesthereof, by a consideration of the following detailed description of oneor more embodiments. Reference will be made to the appended sheets ofdrawings that will first be described briefly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an electronic device having a MEMS device, in accordancewith an embodiment.

FIG. 2 shows a miniature camera having a lens barrel, in accordance withan embodiment.

FIG. 3A shows a miniature camera with the lens barrel having theactuator module disposed therein, in accordance with an embodiment.

FIG. 3B shows the lens barrel and the actuator module in an explodedview, in accordance with an embodiment.

FIG. 4 shows the actuator module having the multiple degree of freedomactuator disposed therein, in accordance with an embodiment.

FIG. 5 shows a multiple degree of freedom actuator, in accordance withan embodiment.

FIG. 6 is an enlarged view showing one sector of the multiple degree offreedom actuator of FIG. 5, in accordance with an embodiment.

FIG. 7 shows the sector of FIG. 6 with the comb drive teeth removed forclarity, in accordance with an embodiment.

FIG. 8 is an enlarged view showing the out-of-plane actuator of FIG. 7,in accordance with an embodiment.

FIG. 9 is an enlarged view showing a portion of the in-plane actuatorand a portion of the out-of-plane actuator of FIG. 6, in accordance withan embodiment.

FIG. 10 is a flow chart showing an example of operation of the multipledegree of freedom actuator, in accordance with an embodiment.

FIG. 11 illustrates a kinematic mount flexure having an electricalcontact, in accordance with an embodiment.

FIG. 12 shows another embodiment of the actuator module having themultiple degree of freedom actuator disposed therein, in accordance withan embodiment.

FIG. 13 is an enlarged view showing a sintered electrical contact havinga silver paste metallization for coupling to a reference voltage, inaccordance with an embodiment.

FIG. 14 is an enlarged view showing a sintered electrical contact havinga silver paste metallization for coupling to a control voltage, inaccordance with an embodiment.

FIG. 15 is a flow chart showing an example of forming electricalconnections to an actuator having silver-paste-metalized electricalcontacts, in accordance with an embodiment.

FIG. 16 is a flow chart showing an example of a process for formingelectrical contacts for MEMS devices, in accordance with an embodiment

FIG. 17 is a diagram showing an illustrative portion of a MEMS waferduring various manufacturing stages during which sintered electricalcontacts are formed on the MEMS wafer, in accordance with an embodiment.

Embodiments of the invention and their advantages are best understood byreferring to the detailed description that follows. It should beappreciated that like reference numerals are used to identify likeelements illustrated in one or more of the figures.

DETAILED DESCRIPTION

A MEMS device such as a MEMS actuator or a MEMS sensor suitable for usein a wide variety of different electronic devices is disclosed inaccordance with various embodiments. The MEMS device may include atleast one sintered electrical contact. The sintered electrical contactmay be formed from an electrical contact having a sintered material suchas a sintered metal powder, a sintered metal paste, or a sintered metalpreform. In one embodiment, a sintered electrical contact may be ametalized electrical contact such as a silver-paste-metalized electricalcontact.

According to an embodiment, a sintered electrical contact (sometimesreferred to herein as a metalized electrical contact) on a MEMS devicemay be formed during wafer level processing by, after releasing the MEMSwafer (e.g., by etching away a material such as an oxide material thatsecures moving or actuating portions of MEMS devices on the wafer),depositing material such as a metal powder, a metal preform, a metalink, or a metal paste such as a silver paste at electrical contactlocations on the MEMS wafer, heating the MEMS wafer (e.g., to sinter thedeposited material) to form the sintered electrical contacts, andsingulating the wafer to form individual MEMS devices with sinteredelectrical contacts such as silver-paste-metalized electrical contacts.

In one embodiment, the MEMS device may be a multiple degree of freedomactuator. The multiple degree of freedom actuator may be adapted for usein a camera, such as a miniature camera, for example. The multipledegree of freedom actuator may be used to either manually orautomatically focus the miniature camera. The multiple degree of freedomactuator may be used to zoom the miniature camera. The multiple degreeof freedom actuator may be used to facilitate centration of an opticalelement. The multiple degree of freedom actuator may be used to provideoptical image stabilization (OIS) for the miniature camera. The multipledegree of freedom actuator may be used to align optics (such as toactively align the optics during use thereof), e.g., provide finealignment for lenses or other optical elements, within the camera. Themultiple degree of freedom actuator may be used for optical correction,e.g., to mitigate undesirable effects of flaws in optical elements. Forexample, a lens may be rotated to place a defect therein in a moredesirable (or less harmful) position. The multiple degree of freedomactuator may be used for any other desired application in an electronicdevice or in any other device.

In accordance with one or more embodiments, the multiple degree offreedom actuator may comprise one or more MEMS actuators. For example,the multiple degree of freedom actuator may comprise linear comb drivesand rotational comb drives.

The multiple degree of freedom actuator may be formed using monolithicconstruction. The multiple degree of freedom actuator may be formedusing non-monolithic construction. The multiple degree of freedomactuator may be formed using contemporary fabrication techniques, suchas etching and/or micromachining, for example. Various other fabricationtechniques are contemplated.

The multiple degree of freedom actuator may be formed of silicon (e.g.,single crystal silicon and/or polycrystalline silicon). The multipledegree of freedom actuator may be formed of various semiconductormaterials such as silicon, germanium, diamond, and/or gallium arsenide.The material of which the multiple degree of freedom actuator is formedmay be doped to obtain a desired conductivity thereof. The multipledegree of freedom actuator may be formed of a metal such as tungsten,titanium, germanium, aluminum, and/or nickel. Any desired combination ofthese and other materials may be used.

Motion control of the multiple degree of freedom actuator and/or itemsmoved by the multiple degree of freedom actuator is disclosed inaccordance with various embodiments. The motion control may be used tofacilitate a desired movement of an item while mitigating undesiredmovement of the item. For example, the motion control may be used tofacilitate movement of a lens along an optical axis of the lens, whileinhibiting other movements of the lens. Thus, the motion control may beused to provide focusing and/or zoom by facilitating movement of thelens in single desired translational degree of freedom while inhibitingmovement of the lens in all other translational degrees of freedom andwhile inhibiting movement of the lens in all rotational degrees offreedom.

In another example, the motion control may facilitate movement of thelens in all three translational degrees of freedom while inhibitingmovement of the lens in all three rotational degrees of freedom. Forexample, focusing and/or zoom, as well as optical image stabilization,may be facilitated by providing movement of the lens in all threetranslational degrees of freedom while inhibiting movement of the lensin all three rotational degrees of freedom.

Thus, an enhanced miniature camera for standalone use and for use inelectronic devices may be provided. The miniature camera is suitable foruse in a wide variety of different electronic devices. For example, theminiature camera is suitable for use in electronic devices such ascellular telephones, laptop computers, televisions, handheld devices,tablets, car cameras, web cams, and surveillance devices.

According to various embodiments, smaller size and enhanced shockresistance are provided. Enhanced shock resistance can result from thesmaller size (and the consequent lower mass) of the miniature camera andits components. Enhanced shock resistance can result from features ofthe multiple degree of freedom actuator discussed herein.

FIG. 1 shows an electronic device 100 having a miniature camera 101 inaccordance with an embodiment. The miniature camera 101 can have amultiple degree of freedom actuator 400, such as in a lens barrel 200thereof. The multiple degree of freedom actuator 400 can facilitatefocus, zoom, optical image stabilization and/or optical correction asdiscussed herein.

In accordance with various embodiments, electronic device may includeany type of MEMS device. The MEMS device may include electrical contactssuch as sintered electrical contacts having a silver-pastemetallization. The electrical contacts on the MEMS device may beconnected to other circuitry using any suitable conductive connectionsuch as conductive epoxy, anisotropic conductive adhesive, solder,solder paste, a mechanical connector or other suitable materials orcomponents for coupling to a sintered electrical contact such as asilver-paste-metalized electrical contact.

The electronic device 100 may be a cellular telephone, a laptopcomputer, a surveillance device, or any other desired device. Theminiature camera 101 may be built into the electronic device 100, may beattached to the electronic device 100, or may be separate (e.g., remote)with respect to the electronic device 100. Further descriptions ofelectronic devices that can include a multiple degree of freedomactuator may be found in U.S. Patent Publication No. 2013/0077168, FiledSep. 28, 2011, which is incorporated herein by reference in itsentirety.

FIG. 2 shows the miniature camera 101 having the lens barrel 200extending therefrom, in accordance with an embodiment. The lens barrel200 may contain one or more optical elements, such as a movable lens301, which may be moved by the multiple degree of freedom actuator 400(see FIG. 5). The lens barrel 200 may have one or more optical elementswhich may be fixed. For example, the lens barrel 200 may contain one ormore lenses, apertures (variable or fixed), shutters, mirrors (which maybe flat, non-flat, powered, or non-powered), prisms, spatial lightmodulators, diffraction gratings, lasers, LEDs and/or detectors. Any ofthese items may be fixed or may be movable by the multiple degree offreedom actuator 400.

The multiple degree of freedom actuator 400 may be used in non-cameraapplications. The multiple degree of freedom actuator 400 may be used tomove either optical or non-optical devices in various applications. Forexample, the multiple degree of freedom actuator 400 may be used to movesamples that are provided for scanning. The samples may be eitherbiological samples or non-biological samples.

Examples of biological samples include organisms, tissues, cells, andproteins. Examples of non-biological samples include integratedcircuits, MEMS devices, solids, liquids, and gases. The multiple degreeof freedom actuator 400 may be used to manipulate structures, light,sound, or any other desired thing.

The optical elements may be partially or fully contained within the lensbarrel 200. The lens barrel 200 may have any desired shape. For example,the lens barrel 200 may be substantially round, triangular, rectangular,square, pentagonal, hexagonal, octagonal, or of any other shape orcross-sectional configuration. The lens barrel 200 may be eitherpermanently or removably attached to the miniature camera 101. The lensbarrel 200 may be defined by a portion of a housing of the miniaturecamera 101. The lens barrel 200 may be partially or completely disposedwithin the miniature camera 101.

FIG. 3A shows an actuator module 300 disposed within the lens barrel200, in accordance with an embodiment. The actuator module 300 maycontain the multiple degree of freedom actuator 400. The multiple degreeof freedom actuator 400 may be completely contained within the lensbarrel 200, partially contained within the lens barrel 200, orcompletely outside of the lens barrel 200. The multiple degree offreedom actuator 400 may be adapted to move optical elements containedwithin the lens barrel 200, optical elements not contained within thelens barrel 200, and/or any other desired items.

FIG. 3B shows the lens barrel 200 and the actuator module 300 in anexploded view, in accordance with an embodiment. The movable lens 301 isan example of an optical element that may be attached to or inmechanical communication with the multiple degree of freedom actuator400 and may be moved thereby. The movable lens 301 can be moved along anoptical axis 410 of the miniature camera 101 to facilitate focus and/orzoom, for example. The multiple degree of freedom actuator 400 may bedisposed between an upper module cover 401 and a lower module cover 402.

Additional optical elements, such as fixed (e.g., stationary) lenses 302may be provided. The additional optical elements may facilitate focus,zoom, and/or optical image stabilization, for example. Any desirednumber and/or type of movable (such as via the multiple degree offreedom actuator 400) and fixed optical elements may be provided.

As shown in FIG. 3B, actuator 400 may include one or more electricalcontacts 404 for providing control signals such as control voltagesand/or reference voltages to actuator 400. In one embodiment, actuator400 includes three electrical contacts 404 (e.g., a positive controlvoltage contact, a reference voltage contact, and a third, unusedcontact). However, this is merely illustrative. In various embodiments,actuator 400 may include any suitable number of electrical contacts 404for providing control signals or any other signals to or from actuator400. In an embodiment, electrical contacts 404 are sintered electricalcontacts such as silver-paste-metalized electrical contacts. Silverpaste on contacts 404 may have a composition that is suitable forconductive attachment to, for example, voltage supply lines (e.g., leadlines from lens barrel 200) using conductive epoxy. Further descriptionsof actuators with electrical contacts that may be metalized using silverpaste may be found in U.S. Patent Publication No. 2012/0120507, FiledNov. 15, 2010, which is incorporated herein by reference in itsentirety.

FIG. 4 shows the actuator module 300, in accordance with an embodiment.The actuator module 300 may be disposed partially or completely withinthe miniature camera 101. The multiple degree of freedom actuator 400may be disposed partially or completely within the actuator module 300.For example, the multiple degree of freedom actuator 400 may besandwiched substantially between an upper module cover 401 and a lowermodule cover 402.

The actuator module 300 may have any desired shape. For example, theactuator module 300 may be substantially round, triangular, square,rectangular, pentagonal, hexagonal, octagonal, or of any other shape orcross-sectional configuration.

In an embodiment, the lens barrel 200 may be substantially round incross-sectional configuration and the actuator module 300 may besubstantially round in cross-sectional configuration. The use of asubstantially round lens barrel 200 and a substantially round actuatormodule 300 may facilitate an advantageous reduction in size. Thereduction in size may be facilitated, for example, because round lensesare commonly preferred. The use of a substantially round lens barrel 200and a substantially round actuator module 300 with round lenses tends toresult in a reduction of wasted volume and thus tends to facilitate areduction in size.

As discussed herein, one or more optical elements, such as the movablelens 301, may be disposed in an opening 405 (e.g., a hole) formed in theactuator module 300. The multiple degree of freedom actuator 400 mayeffect movement of the optical elements along their optical axis 410,for example. Thus, the multiple degree of freedom actuator 400 may moveone or more lenses, such as lens 301, to effect focusing or zoom, forexample.

The actuator module 300 may have cutouts 403 formed therein tofacilitate assembly of the actuator module 300, alignment of themultiple degree of freedom actuator 400 contained therein, and/orelectrical connections to contacts 404. The cutouts 403 and/orelectrical contacts 404 partially disposed within the cutouts 403 may beused to facilitate alignment of the actuator module 300 with respect tothe lens barrel 200.

FIG. 5 shows the multiple degree of freedom actuator 400, in accordancewith an embodiment of the invention. The multiple degree of freedomactuator 400 can provide motion controlled movement in six degrees offreedom for used in a variety of applications. The multiple degree offreedom actuator 400 can provide three degrees of linear ortranslational motion and three degrees of angular or rotational motion.

The multiple degree of freedom actuator 400 can comprise threesubstantially identical sectors 501. Each sector 501 can comprise both atangential or in-plane actuator 502 and a Z-motion or out-of-planeactuator 503. The in-plane actuators 502 can be linear electrostaticcomb drives, for example. The out-of-plane actuators 503 can berotational electrostatic comb drives, for example. The out-of-planeactuators 503 can be linear, e.g., vertical or 2-axis, electrostaticcomb drives, for example. Each of the in-plane actuators 502 and each ofthe out-of-plane actuators 503 can be independently controllable andmovable with respect to one another.

The in-plane actuators 502 and the out-of-plane actuators 503 cancontrol the motion of a platform 504. The platform 504 can define a lensring and can be used to mount one or more lenses. For example, theplatform 504 can mount the lens 301, which can be a focusing lens and/ora zoom lens. The platform 504 can be moved in all six degrees offreedom.

Since the platform 504 can be moved in all six degrees of freedom, itcan facilitate focus, zoom, optical image stabilization, optical elementalignment, and/or optical correction for example. Focus and/or zoom canbe facilitated by translating one or more lenses along a z-axis. Opticalimage stabilization and/or optical element alignment can be facilitatedby translating one or more lenses or another optical element within anx-y plane and/or by rotating the lens or other optical element(s) aboutan x-axis and/or a y-axis.

Although FIG. 5 shows the multiple degree of freedom actuator 400 ashaving three in-plane actuators 502, the multiple degree of freedomactuator 400 can have any number of in-plane actuators 502. For example,the multiple degree of freedom actuator 400 can have one, two, three,four, five, six, or more in-plane actuators 502.

Each in-plane actuator 502 can provide tangential movement of theplatform 504. That is, each in-plane actuator 502 can move a point 511on a periphery of the platform 504 in a direction that is substantiallytangential with respect to the periphery of the platform 504, asindicated by arrow 512.

All of the in-plane actuators 502 can cooperate to provide translationalmovement of the platform 504 within the x-y plane (within the plane ofthe multiple degree of freedom actuator 400). Such x-y plane movement ofthe platform 504 can be used to translate the lens 301 for optical imagestabilization or alignment, for example.

All of the in-plane actuators 502 can cooperate to provide z-axisrotational movement of the platform 504. Such z-axis rotational movementcan be used to rotate a direction sensitive optical element, such as apolarizer or a diffraction grating, for example.

Although FIG. 5 shows the multiple degree of freedom actuator 400 ashaving three out-of-plane actuators 503, the multiple degree of freedomactuator 400 can have any number of out-of-plane actuators 503. Forexample, the multiple degree of freedom actuator 400 can have one, two,three, four, five, six, or more out-of-plane actuators 503.

The out-of-plane actuators 503 can cooperate to provide translationalmovement of the platform 504 along the z-axis (which is perpendicularwith respect to the plane of the multiple degree of freedom actuator400). Such z-axis movement of the platform 504 can be used to translatethe lens 301 for focus and/or zoom, for example. The out-of-planeactuators 503 can cooperate to provide rotational movement of theplatform 504 about the x-axis and/or y-axis. Such rotational movementcan be used to rotate the lens 301 for optical image stabilization oralignment, for example.

FIG. 6 is an enlarged view showing one sector 501 of the multiple degreeof freedom actuator 400 of FIG. 5, in accordance with an embodiment ofthe invention. As shown in FIG. 5, the multiple degree of freedomactuator 400 comprises three sectors 501. The multiple degree of freedomactuator 400 can comprise any desired number of sectors 501. Forexample, the multiple degree of freedom actuator 400 can comprise one,two, three, four, five, six, or more sectors 501.

The in-plane actuators 502 can each comprise a fixed x-y frame 601 and amovable x-y frame 602. Comb fingers or teeth 603 can extend from thefixed x-y frame 601 and the movable x-y frame 602 and can cooperate todefine an electrostatic actuator that effects substantially linearmovement of the movable x-y frame 602 with respect to the fixed x-yframe 601. The movable x-y frame 602 moves within the x-y plane. Themovable x-y frame 602 moves back and forth in the directions indicatedby arrow 512.

The fixed x-y frame 601 of each sector 501 can cooperate to define anouter frame 610 of the multiple degree of freedom actuator 400. Theouter frame 610 can substantially rigidly interconnect each of thesectors 501 to one another.

The out-of-plane actuators 503 can each comprise an out-of plane,deployed z-frame 620 and a movable z-frame 621. Comb fingers or teeth623 can extend from the deployed z-frame 620 and the movable z-frame 621and can cooperate to define an electrostatic actuator that effectsmovement of the movable z-frame 621 with respect to the deployed z-frame620. The movable z-frame 621 rotates so as to provide movement of atleast a portion of the platform 504 substantially along the z axis.

The deployed z-frame 620 can be deployed to a position such that thedeployed z-frame 620 is angularly disposed with respect to the plane ofthe multiple degree of freedom actuator 400. That is, the deployedz-frame 620 can be rotated about a hinge line 551 that passes through aproximal portion 552 of the deployed z-frame 620 so as to cause a distalportion 553 of the deployed z-frame 620 to move out of the plane of themultiple degree of freedom actuator 400 and into the deployed positionof the deployed z-frame 620. The deployed position of the deployedz-frame 620 can be either above or below (on either side of) the planeof the multiple degree of freedom actuator 400.

FIG. 7 shows the sector of FIG. 6 with the teeth 603 and 623 removed forclarity, in accordance with an embodiment of the invention. Motioncontrol features can be used to limit the motion of the in-planeactuators 502 and the out-of-plane actuators 503. The motion controlfeatures can consequently limit the motion of the platform 504, sincethe motion of the platform 504 is controlled by the in-plane actuators502 and the out-of-plane actuators 503.

For example, tangential movement flexures 701, cantilever flexures 702,torsional flexures 703, outer hinge flexures 704, and inner hingeflexures 705 can be used to facilitate motion control.

The tangential movement flexures 701 can facilitate lateral movement ofthe in-plane actuators 502 so as to provide tangential movement of theplatform 504. This can be done while the tangential movement flexures701 inhibit movement of the in-plane actuators 502 in other degrees offreedom.

The cantilever flexures 702 can transfer z-axis motion of theout-of-plane actuators 503 to the platform 504 while accommodating thevarying distance between out-of-plane actuators 503 and the platform504. This can be done while the cantilever flexures 702 inhibit movementof the out-of-plane actuators 503 in other degrees of freedom.

The torsional flexures 703 can facilitate rotational movement of themovable z-frames 621 of the out-of-plane actuators 503 so as to providemovement of the platform 504 along the z-axis. This can be done whilethe torsional flexures 703 inhibit movement of the movable z-frames 621in other degrees of freedom. In particular, the torsional flexures 703inhibit movement of the movable z-frames 621 along the x axis.

The outer hinge flexures 704 can facilitate rotational movement of themovable z-frame 621 of the out-of-plane actuators 503 so as to providemovement of the platform 504 along the z-axis. This can be done whilethe outer hinge flexures 704 inhibit movement of the movable z-frame 621in other degrees of freedom. In particular, the outer hinge flexuresinhibit movement of the y direction.

The inner hinge flexures 705 can facilitate rotational movement of theout-of-plane actuators 503 as the cantilever flexures 702 transferz-axis motion of the out-of-plane actuators 503 to the platform 504.This can be done while the inner hinge flexures 705 inhibit movement ofthe platform 504 in other degrees of freedom.

Each of the out-of-plane actuators 503 can have two proximal lateralsnubber assemblies 706 and one distal lateral snubber assembly 707 toprovide further motion control, for example. The proximal lateralsnubber assemblies 706 can inhibit lateral movement of the movablez-frame 621 with respect to the deployed z-frame 620. The distal lateralsnubber assembly 707 can inhibit later movement of the platform 504 withrespect to the movable z-frame 621.

FIG. 8 is an enlarged view showing the out-of-plane actuator of FIG. 7,in accordance with an embodiment of the invention. The teeth 603 of thein-plane actuators 502 and the teeth 623 out-of-plane actuators 503 areshown.

FIG. 9 is an enlarged view showing a portion of the in-plane actuator ofFIG. 9, in accordance with an embodiment of the invention. Some of themotion control features can be more clearly seen in this view. Forexample, one of the tangential movement flexures 701, one of thecantilever flexures 702, one of the torsional flexures 703, one of theouter hinge flexures 704, and one of the inner hinge flexures 705 can bemore clearly seen.

In operation, the three out-of-plane actuators 503 can move in unison totranslate one or more lenses and thus facilitate focus and/or zoom. Thethree out-of-plane actuators 503 can move independently to rotate one ormore lenses to facilitate optical image stabilization or alignment ofthe lens(es). The three in-plane actuators 502 can move independently totranslate one or more lenses or another optical element to facilitateoptical image stabilization or alignment of the lens(es) or opticalelement.

Any of the in-plane actuators 502 and the out-of-plane actuators 503 canbe biased or moved to a given position that can be considered a zero orcentered position. The centered position can be anywhere along the rangeof travel for the in-plane actuators 502 and the out-of-plane actuators503. The centered position can be an aligned position of the lens(s) orother optical elements. The in-plane actuator(s) 502 and/or theout-of-plane actuator(s) 503 can remain in this centered position untildriven to a different position to effect focus, zoom, or optical imagestabilization.

The state or position of each of the in-plane actuators 502 and each ofthe out-of-plane actuators 503 can be controlled by providing a controlsignal or voltage thereto. Generally, higher voltages will result ingreater movement of the in-plane actuators 502 and the out-of-planeactuators 503.

FIG. 10 is a flow chart showing an example of operation of the multipledegree of freedom actuator 400, in accordance with an embodiment of theinvention. On power up of the electronic device 100 and/or the miniaturecamera 101, the in-plane actuators 502 and/or the out-of-plane actuators503 can move the lens 301 to an aligned position proximate a center oftravel of the lens 301.

More particularly, the out-of-plane actuators 503 can move the lens to aposition proximate the center of travel of the lens 301, as indicated inblock 1001 and the in-plane actuators 502 can cooperate with theout-of-plane actuators 503 to align the lens in all six degrees offreedom, as indicated in block 1002.

During an autofocus process, the lens 301 can be moved by theout-of-plane actuators 503 to a position that provides a desired focusof the miniature camera 101, as indicated in block 1003. This movementcan be accomplished while maintaining the alignment of the lens 301.

During an optical image stabilization process, the in-plane actuators502 and/or the out-of-plane actuators 503 can cooperate to move the lens301 in a manner that provides optical image stabilization as indicatedin block 1004. Aligning the lens 301, focusing with the lens 301, andproviding optical image stabilization with the lens 301 can occurserially, in parallel with one another, or partially serially andpartially in parallel (e.g. can overlap) with one another.

With reference to FIGS. 11-15, electrical routing and contact isdiscussed, in accordance with several embodiments. Such electricalrouting may be used to conduct electrical signals (e.g., controlvoltages) from the lens barrel 200 to the actuator 400 in order tofacilitate focusing, zooming, and/or optical image stabilization, forexample.

FIG. 11 illustrates a top view of an electrical contact 404. As shown inFIG. 11, electrical contact 404 may be attached to an outer frameportion 1106 of actuator 400 by kinematic mount flexures 1102, inaccordance with an embodiment. In various embodiments, the kinematicmount flexures 1102 and the electrical contact 404 may be formed from asingle crystalline substrate, a single crystalline substrate having alayer of polysilicon formed thereon, various semiconductor materialssuch as silicon, germanium, diamond, and/or gallium arsenide, dopedconductive materials, alloys and/or metals such as tungsten, titanium,germanium, aluminum, and/or nickel.

The electrical contact 404 and the kinematic mount flexure 1102 mayfacilitate mounting of the actuator device 400, such as within a lensbarrel 200, as discussed herein. The electrical contact 404 and thekinematic mount flexure 1102 may facilitate electrical communicationbetween the lens barrel and actuators such as actuators 502 and/or 503of the actuator device, as discussed herein. The flexures 1102 may, forexample, accommodate manufacturing imperfections or tolerances of theactuator device 400 and/or the lens barrel 200 while mitigating stressupon the actuator device 400 caused by such imperfections.

According to an embodiment, electrical connection may be made to eitherdesired surface (e.g., top or bottom) of the electrical contact 404.Electrical contacts on a MEMS device such as electrical contacts 404 ofactuator 400 may be provided with a conductive contact pad on one ormore surfaces as described below in connection with, for example FIGS.12 and 13.

A voltage may be applied to actuators such actuators 502 and 503 via theelectrical contacts 404. For example, two of the three contacts 404 maybe used to apply a voltage from the lens barrel 200 to the actuator 400.The third contact 404 may be unused or may be used to redundantly applyone polarity of the voltage from the lens barrel 200 to the actuator400.

Voltages may be applied to actuators such as actuators 502 and/or 503using voltages supplied to contacts 404 that result in translation ofthe platform 504 (e.g., motion of the platform such that the platform504 remains substantially parallel to an outer frame, therebymaintaining alignment of, for example, an optical element such as themovable lens 301 as the optical element is moved, such as along anoptical axis 410) and/or tilting of the platform 504 (e.g., motion ofthe platform such that the platform tilts substantially with respect tothe outer frame, thereby aligning the platform 504 to the outer frame,facilitating optical image stabilization, or lens alignment).

In some embodiments, trenches 1101 may be formed in the kinematic mountflexures 1102 and trenches 1122 may be formed in the electrical contact404. However, this is merely illustrative. If desired, flexures 1102and/or electrical contact 404 may be formed without trenches. Trenches1101 and/or 1122 may, for example, be polysilicon trenches in a singlecrystalline substrate.

In embodiments in which kinematic mount flexures are provided withtrenches, the trenches 1101 may be formed substantially in a center ofeach kinematic mount flexure 1102 and may be formed substantiallyperpendicular to a length of the kinematic mount flexures 1102, forexample. The trenches 1101 may be adapted such that the trenches 1101are suitable to electrically isolate a first portion of the kinematicmount flexure 1102 on one side of the trench 1101 from a second portionof the kinematic mount flexure 1102 on the other side of the trench1101. Thus, in one embodiment, the application of a voltage toelectrical contact 404 on one side of the trench 1101 does notsubstantially affect the kinematic mount flexure 1102 on the other sideof the trench 1101.

As shown in FIG. 11, electrical contact 404 may include an opening suchas opening 1104 formed at least partially between kinematic mountflexures 1102 for that contact 404. As described further in U.S. patentapplication Ser. No. 14/042,214 which is incorporated herein byreference in its entirety, kinematic mount flexures and electricalcontacts such as kinematic mount flexures 1102 and electrical contact404 may comprise a single crystalline substrate having a layer ofpolysilicon formed thereon.

In some embodiments, the single crystalline substrate may beelectrically isolated from the polysilicon, so as to facilitate acommunication of different voltages thereby. For example, the singlecrystalline substrate may be used to communicate one voltage to anactuator and the polysilicon may be used to communicate another voltageto the same actuator to effect actuation thereof.

In some embodiments, at least some portions of the single crystallinesubstrate may be in electrical communication with the polysilicon, so asto facilitate the communication of voltage therebetween. For example,the single crystalline substrate and the polysilicon of one or moreelectrical contacts 404 may be in electrical communication with oneanother such that an electrical connection may be made to either the top(polysilicon) or the bottom (single crystalline substrate) of theelectrical contact 404 with the same effect.

For example, one voltage may be applied to an electrical contact 404 andmay be routed to the actuator via the polysilicon formed upon theactuator device and may be isolated from the single crystallinesubstrate from which the actuator device is formed. The polysilicontrenches may prevent shorting of a voltage applied to the electricalcontact 404 with respect to the single crystalline substrate of theactuator device.

The kinematic mount flexures 1102 may be mechanically continuous. Thus,the kinematic mount flexures 1102 may facilitate mounting of theactuator device to a lens barrel 200 as discussed herein, for example.

The polysilicon trenches 1122 may be formed in the electrical contact404 to provide electrical communication through the electrical contact404. Thus, a voltage applied to one side of the electrical contact 404may be provided to the other side of the electrical contact 404. Anydesired number of the polysilicon trenches 1122 may be formed in theelectrical contact 404.

The use of such trenches 1101 and 1122 may provide substantialflexibility in the routing of voltages, such as through the actuatordevice for the actuation of the actuators thereof, for example. The useof through-the-thickness (top to bottom) polysilicon filled trenches1122 may provide flexibility in the routing of voltages from one surfaceof the actuator device 400 to the other surface thereof. Such trenches1122 may be used at any desired location and are not limited in locationto the electrical contacts 404.

In accordance with an embodiment, a single polysilicon trench 1122 maybe formed in the electrical contact 404 such that the polysilicon trench1122 extends completely through the electrical contact 404 and does notcompletely cross the electrical contact 404 (e.g., such that thepolysilicon trench 1122 does not separate the electrical contact 404into two electrically isolated portions). The polysilicon trench 1122may be used to provide electrical communication between surfaces of theelectrical contact. For example, the polysilicon trench 1122 may be usedto provide electrical communication between a top surface and a bottomsurface of the electrical contact 404.

In accordance with an embodiment, the polysilicon trench 1101 formed inthe single crystalline substrate may have an oxide layer formed thereon.The polysilicon may be formed upon the oxide layer. In one embodiment,the single crystalline substrate of the kinematic mount flexure 1102 maybe formed of doped single crystalline silicon and the polysilicon may beformed of a doped polysilicon. Thus, the single crystalline substrate ofthe kinematic mount flexure 1102 and the polysilicon of the kinematicmount flexure 1102 may both be at least partially conductive and may beused to route voltages (such as to the actuators, for example). Theoxide layer may electrically isolate the polysilicon from the singlecrystalline substrate of the kinematic mount flexure 1102.

An undercut may be formed in the trench 1101 by removing a portion ofthe oxide layer. The portion of the oxide layer may be removed during anetching process, for example.

In accordance with an embodiment, the polysilicon trench 1122 may havethe oxide layer formed thereon. The polysilicon may be formed upon theoxide layer. The electrical contact 404 may be formed of doped singlecrystalline polysilicon and the polysilicon may be formed of dopedpolysilicon. Thus, the electrical contact 404 and the polysilicon may beat least partially conductive and may be used to route voltages. Theoxide layer may be used to electrically isolate the polysilicon from theelectrical contact 404.

A metal contact pad, a silver paste dot or another conductive contactmay be in electrical communication with both the polysilicon and thesingle crystalline silicon. Thus, the conductive contact may be used toapply a voltage to both surfaces (top and bottom) of the electricalcontact 404.

Use of the trenches 1101 and 1122 permits use of the conductive contacton either side of the electrical contact 404. Thus, use of the trenches1101 and 1122 enhances the flexibility of providing voltages to theactuator device.

An undercut may be formed in the trench 1122 by removing a portion ofthe oxide layer. A portion of the oxide layer may be removed during anetching process, for example.

In accordance with an embodiment, the kinematic mount flexure 1102 maybe provided having no polysilicon trench 1101 formed therein and theelectrical contact 404 may be provided having no polysilicon trench 1122formed therein. Thus, the single crystalline silicon substrate, forexample, may be electrically and mechanically continuous. According toan embodiment, electrical connection may be made to either desiredsurface (e.g., top or bottom) of the electrical contact 404.

In accordance with an embodiment, a polysilicon layer may be formed uponthe kinematic mount flexures 1102 and/or the electrical contact 404. Thepolysilicon layer may provide electrical communication from theelectrical contact 404 to the actuators, for example.

In accordance with an embodiment, the polysilicon layer may be formedupon an oxide layer to electrically isolate the polysilicon layer from asingle crystalline substrate, for example. Thus, an electricalconnection providing one voltage to the polysilicon layer may be madevia the top of the electrical contact 404 and an electrical connectionproviding a different voltage to the single crystalline substrate may bemade via the bottom of the electrical contact 404.

In accordance with an embodiment, the polysilicon layer may extend overthe top surface of the electrical contact 404 and down along at leastone side thereof. The polysilicon layer may be electrically isolatedfrom the single crystalline substrate by the oxide layer. A portion ofthe oxide layer may be etched away during processing, forming anundercut. A metal contact pad, silver paste dot, or other conductivecontact may be formed to the single crystalline substrate to facilitateelectrical contact therewith.

In accordance with an embodiment. The electrical contact 404 and thekinematic mount flexure 1102 may facilitate mounting of the actuatordevice, such as within a lens barrel 200, as discussed herein. Theelectrical contact 404 and the kinematic mount flexure 502 mayfacilitate electrical communication between the lens barrel andactuators of the actuator device, as discussed herein. The flexures 1102may, for example, accommodate manufacturing imperfections or tolerancesof the actuator device and/or the lens barrel while mitigating stressupon the actuator device caused by such imperfections.

In accordance with an embodiment, the polysilicon layer may becontinuous among multiple actuators. Thus, a single electrical signal(e.g., voltage) may readily be applied to multiple actuators to effectsubstantially identical and substantially simultaneous control thereof.That is, the multiple actuators may tend to move substantially in unisonwith respect to one another in response to the single electrical signal.

In accordance with an embodiment, the polysilicon layer may bediscontinuous among various actuators. Thus, separate electrical signals(e.g., voltage) may readily be applied independently to each of theactuators to effect substantially independent control thereof. That is,multiple actuators may be controlled so as to move substantially innon-unison with respect to one another in response to the differentelectrical signals.

In accordance with several embodiments, separated MEMS structures may beprovided. Separated structures may be used to provide mechanical and/orelectrical isolation thereof, such as for structures of the actuatordevice, for example. Structures made of the same material may beseparated from one another. Structures made of different materials maybe separated from one another. Structures may be separated to facilitaterelative motion to one another. Structures may be separated to define adesired device or structure by discarding a separated structure.Structures may be separated to allow different voltages to be present ateach structure.

In accordance with an embodiment, a trench in a MEMS device may have anarrow portion or pinch formed therein. The trench may be etched intothe substrate. For example, a deep reactive-ion etching (DRIE) processmay be used to form the trench. Examples of DRIE processes are disclosedin U.S. patent application Ser. No. 11/365,047, filed Feb. 28, 2002, andin U.S. patent application Ser. No. 11/734,700, filed Apr. 12, 2007 allof which are incorporated herein by reference in their entirety.

In one embodiment, the trench may be etched part of the way from the topof the substrate to the bottom thereof. In another embodiment, thetrench may be etched completely through the substrate (e.g., all of theway from the top of the substrate to the bottom thereof). A bottomportion of the substrate through which the trench does not extend may beremoved during subsequent processing. The trench may have any desiredlength. The trench, as well as any other trench discussed herein, may belocally etched, such as via the DRIE process.

A gap may be defined by the pinch. The pinch may be formed on either oneside or both sides of the trench. The gap may be defined as a portion ofthe trench that is narrower than adjacent portions of the trench.

The trench, including the gap, may taper slightly from top to bottom. Ataper angle may result from the DRIE process when the trench is etchedinto the substrate. In one embodiment, the taper angle may be less thanone degree. For example, the taper angle may be in the range ofapproximately 0.6 to approximately 0.8 degrees.

A bottom portion of the substrate defined beyond the bottom of thetrench may be removed during subsequent processing such that afterremoval the trench extends completely through the substrate.

In accordance with an embodiment, an oxide layer may be formed withinthe trench. The oxide layer may comprise silicon dioxide, for example.In one embodiment, the oxide layer may be formed by a thermal growthprocess. The oxide layer may substantially fill the gap. The oxide layermay completely fill the gap. By filling the gap, the oxide layerfacilitates the separation of a subsequently formed polysilicon materialinto two separate portions thereof.

In accordance with an embodiment, the oxide defines four regions. Theoxide layer separates the substrate into two regions and separates thetrench into two regions (each of which may be filled with polysilicon),as discussed in further detail herein.

In accordance with an embodiment, a second semiconductor material, suchas a polysilicon, may be formed upon the oxide layer. Thus, thesubstrate and the material with which the trench is filled may comprisea first semiconductor material and a second semiconductor material. Thefirst semiconductor material and the second semiconductor material maybe the same semiconductor materials or may be different semiconductormaterials. The first semiconductor material and the second semiconductormaterial may be any desired semiconductor materials. Non-semiconductormaterials may be used as discussed herein.

In accordance with an embodiment, during a wafer thinning process, thebottom portion of the substrate may be removed such that the trenchextends completely through the substrate.

In accordance with an embodiment, the taper angle and a consumption ofthe silicon during the thermal growth process cooperate to separate thepolysilicon into two portions. In one embodiment, the separation is atthe thinnest part of the trench (e.g., at the pinch).

In accordance with an embodiment, all or a portion of the oxide may beremoved.

In accordance with an embodiment, the single crystalline siliconsubstrate may be separated into two portions and the polysilicon mayeach be separated into two portions. Each portion of the substrate andeach portion of the polysilicon may be mechanically and/or electricallyisolated from each other portion thereof. Indeed, each portion of thesubstrate may be mechanically and/or electrically isolated from eachother, and from each portion of the polysilicon. Each portion of thepolysilicon may be mechanically and/or electrically isolated from eachother, and from each portion of the substrate. Thus, structures madefrom the same material may be separated from one another and structuresmade from different material may be separated from one another.

In the embodiments including a pinch, the use of the pinch facilitatesthe separation of two portions of the polysilicon with respect to oneanother. In other embodiments, an etch process facilitates theseparation of two portions of a polysilicon with respect to one another.

In accordance with an embodiment, a DRIE trench etch process may be usedto form a trench in substrate formed from a first semiconductor. Inaccordance with an embodiment, a thermal oxidation process may be usedto form an oxide layer in the trench. The oxide layer may also be formedupon a top of the substrate. In accordance with an embodiment, apolysilicon deposition process may be used to deposit a polysilicon overthe oxide layer. The polysilicon may fill the trench and may extend overthe entire top of the substrate or over a portion of the top of thesubstrate.

In accordance with an embodiment, a portion of the polysilicon and asubstantially corresponding portion of the oxide layer may be removed,such as by etching (e.g., an oxide etch). The removal of the polysiliconand the oxide layer may form a trough.

In accordance with an embodiment, an etch process such as a pinch offDRIE etch process may result in the formation of a pinch or gap thatseparates the polysilicon into two portions. At this point inprocessing, the trench may not extend completely from a top to a bottomof the substrate. The gap may be functionally similar to the pinch. Thegap facilitates the separation of portions of the polysilicon from oneanother.

In accordance with an embodiment, a wafer thinning process may be usedto remove a sufficient portion of the bottom of the substrate such thatthe trench extends completely from the top to the bottom of thesubstrate.

In accordance with an embodiment, an isotropic oxide etch process may beapplied to the substrate. The isotropic oxide etch may be used to removea portion of the oxide layer. The isotropic oxide etch process mayrelease four structures (i.e., the two portions of the substrate and thetwo portions of the polysilicon) from each other. Thus, the fourstructures may be mechanically and/or electrically isolated from oneanother. The isotropic oxide etch process may be used to selectivelyrelease or separate any desired structures or portions of structuresfrom one another.

In accordance with an embodiment, both the single crystalline siliconsubstrate and the polysilicon may be separated into two portions each.Each of the two portions of the single crystalline substrate may bemechanically and electronically isolated from one another and from eachof the two portions of the polysilicon. Each of the two portions of thepolysilicon may be mechanically and electrically isolated from oneanother and from each of the two portions of the single crystallinesubstrate.

In one embodiment, moving polysilicon structures are separated fromstationary polysilicon structures and stationary single crystallinestructures. Advantage may be taken of the mechanical separation of themoving polysilicon structures with respect to the stationary polysiliconstructures to facilitate movement of the moving polysilicon structureswith respect to the stationary polysilicon structures. Advantage may betaken of the electrical separation of the moving polysilicon structureswith respect to the stationary polysilicon structures to facilitate theapplication of different voltages to the moving polysilicon structuresand the stationary polysilicon structures.

In accordance with an embodiment, a silicon fillet may fall off or beremoved from the actuator device during fabrication thereof and thus maynot form a part thereof. The silicon fillet is material that is removedfrom the single crystalline substrate to form the actuator device. Afteretching, the moving polysilicon will be free to move with respect to thestationary polysilicon. Thus, the moving polysilicon will be separatedfrom the stationary polysilicon.

A guard trench may be provided, in accordance with several embodiments.The guard trench may be used for supporting a polysilicon layer duringthe etching of an oxide layer and for limiting the resulting etch of theoxide layer behind the guard trench, for example. In one embodiment, theguard trench may be a blind trench that provides an increased pathlength of the oxide layer to be etched such that the etch is inhibitedfrom extending to portions of the oxide layer where etching is notdesired. The use of the guard trench permits a larger tolerance orvariation in etch parameters (such as echant, echant concentration,temperature, duration) without the variation undesirably affectingdevice operation or performance.

In accordance with an embodiment, a guard trench may be formed proximatea regular trench in a substrate. The regular trench may provide anydesigned function. For example, the polysilicon in the trench mayconcentrate voltages across the actuator device to one or moreactuators. The guard trench may be deeper than the regular trench, thesame depth as the regular trench, or shallower than the regular trench.The guard trench may be substantially parallel with respect to theregular trench or may be non-parallel with respect to the regulartrench. The guard trench and/or the regular trench may be formed by aDRIE process or by any other desired method.

In accordance with an embodiment, the oxide layer may comprise silicondioxide and may be formed by a thermal oxidation process. In accordancewith an embodiment, the polysilicon may completely fill the guard trenchand/or the regular trench.

In accordance with an embodiment, during surface etching, a portion ofthe oxide layer and the polysilicon may be removed from the top surfaceof the substrate. For example, a portion of the oxide layer and thepolysilicon may be removed from the top surface of the substrate tofacilitate a desired routing of voltages upon a surface of an actuatordevice.

In accordance with an embodiment, during a wafer thinning process, abottom portion of the substrate may be removed. Removal of the bottomportion of the substrate may result in the regular trench and/or theguard trench extending from a top surface of the substrate to a bottomsurface of the substrate. For example, removal of the bottom portion ofthe substrate may result in the regular trench extending from the topsurface of the substrate to the bottom surface of the substrate and theguard trench not extending from the top surface of the substrate to thebottom surface of the substrate. Thus, the guard trench may be a blindtrench and the regular trench may be a through trench, for example.

In accordance with an embodiment, after an isotropic etch, a portion ofthe polysilicon may be released by the formation of an undercut. Theguard trench may inhibit the undercut from propagating to the regulartrench such that the polysilicon proximate the regular trench is notreleased from the substrate and thus remains substantially attachedthereto. In this manner, the guard trench tends to protect the regulartrench from undesirable undercut and release.

In one embodiment, the guard trench is formed proximate the regulartrench in the substrate, the guard trench is irregular (e.g., curved) inshape and not parallel to the regular trench. The guard trench tends tomaintain the oxide layer in an area upon the substrate where the oxidelayer is used to connect a flexure, such as a deployment torsionalflexure, or after flexure.

FIG. 12 shows another embodiment of actuator module 300. In the exampleof FIG. 12, cutouts 403 in upper module cover 401 include surfaces 1202that are formed at an obtuse angle with respect to top surface 1204 ofupper module cover 401. However, this is merely illustrative. Cutouts403 may be formed in any suitable shape for facilitating electricalconnection to electrical contacts 404.

Electrical contacts 404 may be metalized electrical contacts such assilver-paste-metalized electrical contacts or other electrical contactsformed by sintering material onto a substrate of a MEMS device. In theexample of FIG. 12, actuator module 300 includes three electricalcontacts 404A, 404B, and 404C, each having silver paste 1200 on theelectrical contact. Electrical contacts such as electrical contacts404A, 404B, and 404C for one or more embodiments may be provided with asilver paste dot, may be substantially covered in silver paste, or maybe otherwise metalized using silver paste according to variousembodiments.

In this example, electrical contact 404A may be configured to beconnected to one or more leads (e.g., control leads) that, duringoperation of actuator 400, supply a control voltage such as a positivecontrol voltage to contact 404A, electrical contact 404B may beconfigured to be attached to a lead (e.g., a reference lead) that,during operation of actuator 400, supplies a reference voltage such as aground voltage to contact 404B, and electrical contact 404C may be anunused electrical contact (e.g., an electrical contact that, in anassembled product, is substantially free of electrical connections toexternal circuitry). Unused electrical contacts such as contact 404C maybe sintered electrical contacts such as silver-paste metalized or may benon-metalized contacts. Unused contacts 404C may be identified by achamfered corner (not shown) on the contact or on module covers 401and/or 402. In an assembled product, the lens barrel may have electricalleads for providing the reference voltage and the control voltage tocontacts 404. Each electrical lead may include a first end that isconnected to a silver paste dot on an electrical contact 404 (e.g.,using conductive epoxy) and an opposing second end that is connected tothe lens barrel.

As shown in FIG. 12, in some embodiments, upper module cover 401 andlower module cover 402 may have additional cutouts 1206 on outer edgesof the module covers. Cutouts 1206 may define a circumferential shapefor module 300 and may help facilitate alignment of the actuator module300 with respect to the lens barrel 200.

It should be appreciated that the example of FIG. 12 is merelyillustrative. In various embodiments, actuator 400 may include threeelectrical contacts, less than three electrical contacts, more thanthree electrical contacts, more than one unused electrical contact, orno unused electrical contacts. In various embodiments, some or all ofthe electrical contacts 404 described herein may be sintered electricalcontacts such as silver-paste metalized electrical contacts.

FIGS. 13 and 14 show examples of electrical contacts that haveconductive portions formed by sintering a material on the electricalcontact. In one suitable embodiment that is sometimes discussed hereinas an example, sintered electrical contacts are electrical contacts thathave been metalized using silver paste. However, this is merelyillustrative. In various embodiments, electrical contacts on a MEMSdevice may be formed by sintering any suitable material (e.g., a metalpowder, a metal ink, a metal preform, or a metal paste such as silverpaste) onto a substrate of the MEMS device.

In the example of FIG. 13, silver paste 1200 is provided on a contact404. Contact 404 of FIG. 13 may, for example, be a contact such ascontact 404B of FIG. 12 that is to be connected to an electricalreference voltage (e.g., a ground voltage) for actuator 400. In theexample of FIG. 14, silver paste 1200 is provided on a contact 404having multiple edge segments 1400. Contact 404 of FIG. 14 may, forexample, be a contact such as contact 404A of FIG. 12 for coupling to acontrol voltage such as a positive control voltage. Segments 1400 may beused in accordance with one or more embodiments to identify a particularcontact having segments 1400 as the contact to be connected to positivecontrol voltage leads (e.g., as opposed to a reference voltage lead),and/or may be used as contact points for multiple leads.

As examples, a positive control voltage may, for example, be a voltagebetween 31V and 32V, between 30V and 32V, between 31.3V and 31.5V,between 20V and 31.4V, less than 32V, less than 31.4V, greater than 1V,or any other suitable positive control voltage for operating actuator400. In one embodiment, silver-paste-metalized contacts 404 of this typemay be configured to receive a voltage of less than, for example, 32Vand/or a current of less than, for example, 50 micro Amperes withoutcausing damage to the contact and/or the actuator.

Silver paste 1200 may be formed on each contact 404 in a silver pastedot having a size characterized by a width W and a length L. Width W ofeach silver paste dot may, as examples, be greater than 180 microns,greater than 170 microns, greater than 150 microns, greater than 100microns, between 180 microns and 280 microns, between 180 microns and300 microns, between 180 microns and 380 microns, between 240 micronsand 320 microns, between 275 microns and 285 microns, or less than 300microns. Length L of each silver paste dot may, as examples, be greaterthan 120 microns, greater than 110 microns, greater than 100 microns,greater than 50 microns, between 120 microns and 250 microns, between120 microns and 200 microns, between 130 microns and 170 microns,between 120 microns and 170 microns between 145 microns and 155 microns,or less than 200 microns.

Silver paste dots 1200 on electrical contacts 404 may be optimized forconnection (e.g., to voltage supply leads) using conductive epoxy inaccordance with an embodiment. In other embodiments, silver paste dots1200 may be connected to, for example, voltage supply leads using otherconductive coupling components or materials such as solder, anisotropicconductive film, or mechanical connector structures.

The silver paste dots of FIGS. 13 and 14 are formed on electricalcontacts 404 of actuator 400. However, it should be appreciated thatthis is merely illustrative. In various embodiments, electrical contactson any suitable MEMS device (e.g., a MEMS sensor, a MEMS actuator, orother types of MEMS device) may be metalized by sintering metal onto theMEMS devices (e.g., by sintering a silver paste on the MEMS device toform a silver-paste-metalized electrical contact).

FIG. 15 is a flow chart of an illustrative process 1500 of electricallyconnecting a MEMS device such as actuator 400 having at least first,second, and third silver-paste-metalized electrical contacts of the typedisclosed herein. For example, the process 1500 may be used toelectrically connect actuator 400 to a lens barrel 200.

At block 1502, a MEMS device such as a MEMS actuator having multipledegrees of freedom with motion control to limit undesirable movement maybe provided that includes silver-paste-metalized electrical contacts.For example, in accordance with an embodiment, the provided MEMS devicemay include first, second, and third silver-paste-metalized electricalcontacts. Each silver-paste-metalized electrical contact may include asilver paste dot such as silver paste dot 1200 of, for example, FIGS. 13and 14.

At block 1504, a first silver-paste-metalized electrical contact may becoupled to a control voltage such as a positive control voltage, forexample, using conductive epoxy. The conductive epoxy may be used toconductively secure the silver paste dot on the firstsilver-paste-metalized electrical contact to one or more lead lines suchas compliant leads lines (e.g., from a lens barrel) that minimize strainon the electrical contact.

At block 1506, a second silver-paste-metalized electrical contact may becoupled to a second voltage such as a reference voltage (e.g., anelectrical ground voltage) using conductive epoxy. The first and secondsilver-paste-metalized electrical contacts may be coupled to therespective voltages as described above in connection with blocks 1504and 1506 while leaving the third silver-paste-metalized electricalcontact (e.g., a silver-paste-metalized electrical contact having achamfered edge) substantially free of conductive epoxy (for example).Leaving the third silver-paste-metalized electrical contactsubstantially free of conductive epoxy may include leaving the thirdsilver-paste-metalized electrical contact substantially free of allelectrical contacts. If desired, as described herein, the thirdsilver-paste-metalized electrical contact may be replaced by anelectrical contact that is not silver-paste-metalized.

A MEMS actuator may have multiple degrees of freedom. Once connected(e.g., using the process 1500), the MEMS actuator may receive controlsignals (e.g., voltages) that result in motion control to limitundesirable movement, to focus, to zoom, for optical imagestabilization, and/or for alignment of optical elements for a miniaturecamera (as examples).

A MEMS actuator can embed or nest plural electrostatic drives, such aslinear and rotational comb drives, to tend to minimize space, e.g., realestate, used therefore. Any desired number of electrostatic drives canbe nested in any desired fashion.

FIG. 16 is a flow chart of an illustrative process 1600 by whichelectrical contacts for MEMS devices may be formed. For example, theprocess 1600 may be used to form silver-paste-metalized electricalcontacts on a MEMS device in accordance with an embodiment.

At block 1602, a MEMS wafer (e.g., a substrate having a plurality ofunsingulated MEMS devices such as MEMS actuators and/or MEMS sensors)may be provided. The MEMS wafer may, for example, include a plurality ofMEMS devices formed in a silicon substrate using various semiconductorprocessing techniques. One or more of the MEMS devices on the MEMS wafermay have one or more movable or actuatable portions that are secured bya material such as an oxide material on the substrate.

At block 1604, release operations and/or coating operations may beperformed on the MEMS wafer. Performing release operations may includereleasing the secured movable or actuatable portions of the MEMS devices(e.g., by etching away or otherwise removing the securing material). Forexample, an oxide material on the wafer that secures the movable oractuatable portions may be etched away in a hydrofluoric vapor etchprocess or other suitable etch process that releases that movable oractuatable portions of the MEMS devices on the MEMS wafer. In someembodiments, at block 1604, coating operations may be performed thatform an additional layer such as an insulating layer on the MEMS wafer.For example, an additional layer such as a silicon nitride layer or analuminum oxide layer may be deposited on the wafer or an additionallayer such as an oxide layer may be grown on the wafer.

At block 1606, a material such as a sintering material (e.g., a metalpowder, a metal preform, a metal ink, or a metal paste such as a silverpaste) may be deposited on the released and/or coated MEMS wafer. Thematerial may be deposited at locations on the wafer at which electricalcontacts are to be formed. Depositing the material after the securingmaterial has been removed (e.g., on a “released” MEMS wafer) may helpprevent damage to electrical contacts on the MEMS devices caused by theetching process. In embodiments in which an additional insulating layeris formed at block 1604, the sintering material may, in someembodiments, be deposited onto the insulating layer.

At block 1608, sintering operations may be performed on the releasedand/or coated MEMS wafer that includes the deposited sintering material.Sintering operations may include baking the MEMS wafer to dry thedeposited material and firing the MEMS wafer so that the depositedmaterial diffuses into the wafer substrate, thereby forming Ohmiccontacts with the MEMS devices. In configurations in which the sinteringmaterial is deposited on an insulating layer, sintering operations mayinclude diffusing the sintering material through the insulating layerinto the wafer substrate.

Baking the MEMS wafer may include heating the MEMS wafer at a bakingtemperature (e.g., a temperature between 100 C and 200 C, a temperatureof between 140 C and 160 C, or a temperature of at least 100 C) for abaking time (e.g., less than 30 minutes, less than 60 minutes, less than10 minutes, more than 5 minutes, or between 5 minutes and 15 minutes).Firing the MEMS wafer may include heating the MEMS wafer at a sinteringtemperature (e.g., a temperature greater than 700 C, greater than 800 C,greater than 850 C, greater than 900 C, between 700 C and 1000 C,between 800 C and 900 C, or less than 1000) for a sintering time (e.g.,a time of less than 30 minutes, less than 60 minutes, less than 10minutes, more than 5 minutes, or between 5 minutes and 15 minutes).

In one embodiment, firing the MEMS wafer may include heating the MEMSwafer from a temperature below 100 C to a temperature above 800 C in5-15 minutes, holding the temperature of the MEMS wafer at greater than800 C for 5-15 minutes, reducing the temperature of the MEMS wafer fromgreater than 800 C to less than 100 C in 5-15 minutes and cooling theMEMS wafer for 1-10 hours. In one embodiment, sintering operations mayinclude firing the MEMS wafer at a temperature of at least 900 C so thatan oxide layer grows on the wafer substrate during sintering operations.

At block 1610, the MEMS wafer may be singulated (diced) into individualMEMS devices each having one or more sintered electrical contacts suchas silver-paste-metalized electrical contacts.

At block 1612, packaging operations may be performed for each MEMSdevice (e.g., a MEMS device such as a MEMS actuator havingsilver-paste-metalized contacts may be mounted in a lens barrel of acamera in a portable electronic device and coupled to control leadsusing conductive epoxy).

FIG. 17 is a flow diagram showing a portion of a MEMS wafer duringvarious manufacturing stages during which sintered electrical contactsare formed on the MEMS wafer according to an embodiment.

As shown in FIG. 17, a portion of a MEMS wafer 1701 may include asubstrate such as substrate 1700 (e.g., a silicon substrate). A securingmaterial such as material 1704 may secure moving portions 1702 of a MEMSdevice formed in substrate 1700. For example material 1704 may be anoxide material. MEMS wafer 1701 having securing material 1704 may beprovided to processing equipment such as etching and coating equipment1706. Etching and coating equipment 1706 may include etching equipment(e.g., equipment for performing etching processes such as hydrofluoricvapor etch processes) for removing material 1704 from MEMS wafer 1701and/or coating equipment (e.g., equipment for coating MEMS wafer 1701 inadditional layers such as insulating layer 1708).

Following removal of material 1704 (and optional addition of a coating1708), MEMS wafer 1701 may be provided to additional processingequipment such as deposition and sintering equipment 1710. Depositionand sintering equipment 1710 may include equipment for depositingsintering materials such as metal powders, metal preforms, metal inks,or metal pastes such as silver paste onto a surface 1714 of MEMS wafer1701. Deposition and sintering equipment 1710 may include heatingequipment for performing sintering operations such as baking operationsand firing operations that cause the deposited sintering material to dryand diffuse into substrate 1700, thereby forming sintered electricalcontacts 1712 in Ohmic contact with substrate 1700. In configurations inwhich an insulating layer 1708 is deposited on wafer 1701, depositionand sintering equipment may cause the sintering material to diffusethrough layer 1708 into substrate 1700, thereby forming a sinteredelectrical contact that forms an Ohmic contact with substrate 1700through layer 1708.

Following formation of sintered electrical contacts such as contact 1712on MEMS wafer 1701, MEMS wafer 1701 may be provided to furtheradditional processing equipment such as singulation and packagingequipment 1716 that dices and/or packages individual MEMS devices suchas MEMS actuators or MEMS sensors having sintered electrical contactsfrom MEMS wafer 1701.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed as new and desired to be protected is:
 1. A devicecomprising: a microelectromechanical systems (MEMS) device formed from awafer substrate, the MEMS device including a platform formed in thewafer substrate and defining an optical aperture having an optical axis,the optical aperture configured to transmit light therethrough, and aplurality of MEMS actuators formed in the wafer substrate and configuredto move the platform with respect to the optical axis; and a sinteredelectrical contact formed directly on the wafer substrate of the MEMSdevice.
 2. The device as recited in claim 1, wherein the sinteredelectrical contact comprises a sintered material selected from the groupconsisting of a sintered metal paste, a sintered metal powder, asintered metal ink, and a sintered metal preform.
 3. The device asrecited in claim 1, wherein the sintered electrical contact comprises asilver-paste-metalized electrical contact.
 4. The device as recited inclaim 1, wherein the plurality of MEMS actuators includes: at least oneout-of-plane MEMS actuator configured to move the platform along theoptical axis; and at least one in-plane MEMS actuator configured to movethe platform in a direction that is generally perpendicular to theoptical axis.
 5. The device as recited in claim 4, wherein the MEMSdevice comprises three in-plane MEMS actuators that are configured tocooperate to move the platform.
 6. The device as recited in claim 5,wherein the out-of-plane MEMS actuator is nested at least partiallywithin the three in-plane MEMS actuators.
 7. The device as recited inclaim 1, further comprising: a lens barrel with an electrical lead; anda conductive epoxy that connects the electrical lead to the sinteredelectrical contact.
 8. The device as recited in claim 3, wherein thesilver-paste-metalized electrical contact comprises a silver paste dotwith a width that is between 180 microns and 300 microns and a lengththat is between 120 microns and 170 microns.
 9. The device as recited inclaim 1, wherein: the device comprises a camera having a lens; the MEMSdevice is configured to move the lens via the platform; and the sinteredelectrical contact is attached to an outer frame portion of the MEMSdevice by at least one kinematic mount flexure having a trench.
 10. Thedevice as recited in claim 1, wherein the device comprises a portableelectronic device.
 11. The device of claim 1, further comprising: aninsulating layer deposited over the wafer substrate; and wherein thesintered electrical contact is diffused through the insulating layer andinto the wafer substrate to be in Ohmic contact with the wafersubstrate.
 12. The device of claim 1, further comprising: a lens barrelhaving the MEMS device disposed therein; and a movable lens disposedwithin the lens barrel, the movable lens being coupled to move with theplatform of the MEMS device and to direct light through the opticalaperture.
 13. The device of claim 12, wherein: the MEMS device furtherincludes a flexure; and the sintered electrical contact is formed on theflexure.
 14. A method, comprising: providing a microelectromechanicalsystems (MEMS) wafer having a plurality of MEMS devices, each of theplurality of MEMS devices including a platform formed in the MEMS waferand defining an optical aperture having an optical axis, the opticalaperture configured to transmit light therethrough, and a plurality ofMEMS actuators formed in the MEMS wafer and configured to move theplatform with respect to the optical axis; releasing at least onemovable portion of each of the plurality of MEMS devices; depositing amaterial on the MEMS wafer; and forming a plurality of sinteredelectrical contacts directly on the MEMS wafer by sintering thematerial.
 15. The method as recited in claim 14, wherein the depositingcomprises depositing the material on the MEMS wafer after the releasing.16. The method as recited in claim 15, wherein the forming comprisesheating the MEMS wafer so that the material diffuses through aninsulating layer into a substrate of the MEMS wafer.
 17. The method asrecited in claim 16, wherein the heating comprises heating the MEMSwafer to a temperature that is sufficient to allow oxide growth duringthe heating.
 18. The method as recited in claim 14, wherein thedepositing comprises depositing at least one of a metal paste, a metalpreform, a metal ink, or a metal powder.
 19. The method as recited inclaim 14, wherein the depositing comprises depositing silver on the MEMSwafer.
 20. A method, comprising: providing a microelectromechanicalsystems (MEMS) device having sintered first and secondsilver-paste-metalized electrical contacts formed directly on a wafersubstrate portion of the MEMS device, the MEMS device further includinga platform formed in the wafer substrate portion and defining an opticalaperture having an optical axis, the optical aperture configured totransmit light therethrough, and a plurality of MEMS actuators formed inthe wafer substrate portion and configured to move the platform withrespect to the optical axis; coupling the first silver-paste-metalizedelectrical contact to a control lead; and coupling the secondsilver-paste-metalized electrical contact to a reference lead.
 21. Themethod as recited in claim 20, further comprising: providing a controlvoltage to the first silver-paste-metalized electrical contact using thecontrol lead; and providing a reference voltage to the secondsilver-paste-metalized electrical contact using the reference lead. 22.The method as recited in claim 20, wherein the MEMS device is coupled toa lens of a camera, the method further comprising: adjusting a positionof the lens using the MEMS device by applying a voltage to the firstsilver-paste metalized electrical contact.
 23. The method as recited inclaim 20, wherein the MEMS device is disposed within a lens barrel of acamera in a portable electronic device, wherein the first and secondsilver-paste-metalized electrical contacts are each attached to an outerframe portion of an actuator of the MEMS device by at least onekinematic mount flexure having a trench, and wherein the lens barrelcomprises the control lead, the method further comprising: focusing thecamera by applying a control voltage to the first silver-paste-metalizedelectrical contact with the control lead.